yes, I have activated Internet Connection Sharing
That may be your problem. You don't need ICS running if you are using a router, in fact running ICS and a router will cause no end of problems as both ICS and the router will be trying to provide the IP addresses via DHCP....
Plug the modem into the router,
Plug the desktop into the router via the ethernet port
PLug other computers into the router LAN ports (if available)
Disable ICS & dial up ADSL connection on the desktop
Make sure your router DHCP server is set to "enable",
Setup router with the ISP info which is probably:
Login name
Password
VPI:0
VCI:38
PPPoA for ADSL
Now on each client computer make sure that "obtain IP address automatically" is selected under the LAN connection (Control panel > Network COnnections > Local Area Network, click TCP/IP and select properties).
You could manually configure IP addresses for the client computers if you prefer (BUT remember to disable DHCP in the router). To do this go to the LAN connections, and click Properties for TCP/IP. Manually assign the following IP addresses:
IP: 192.168.1.2 (for 1st computer, 192.168.1.3 for the second and so on).
Subnet: 255.255.255.0
Gateway: 192.168.1.1 (the routers IP address)
DNS servers: These are supplied by your ISP. You may not need to enter anything here, I seem to remember a problem when I couldn't access the internet without entering them. What ISP are you with?
Good luck
Edited because i forgot the wireless bit:
When you have just the router and desktop connected to the Internet, then use the Desktop to configure the wireless newtork.
Login to the router:
http://192.168.1.1 user: admin
pass: admin
(unless changed by you)
Under wireless settings (not familiar with your router, but they are pretty similar):
choose a name for your SSID, can be anything and just identifies your network (i.e. Virgin). Best to change it from the default.
Under WEP key settings:
Enter a password, again can be anything. It uses this phrase to calculate the WEP encryption keys. And then click generate. Write down the Key 1. If you are using Linksys PCMCIA wireless adaptors, you can recreate the key on the client computers by simply entering the passphrase.
On the client computers, under the wireless settings, make sure that encryption is set to WEP, the strength is the same as the routers (i.e. 64bit), and that Key1 is the same as the one you just generated. If your router is set to broadcast the SSID you will see your network, if not, you may have to manually enter the network name (i.e. Virgin)....